253 THEORY OF RESPIRATION. 



state ; that is, they will again acquire the power of giv- 

 ing off oxygen. 



For every volume of oxygen which the globules can 

 give off, there will be formed (as carbonic acid con- 

 tains its own volume of oxygen, without condensation) 

 neither more nor less than an equal volume of carbonic 

 acid. For every volume of oxygen which the globules 

 are capable of absorbing, no more carbonic acid can 

 possibly be separated than that volume of oxygen can 

 produce. 



When carbonate of protoxide of iron, by the ab- 

 sorption of oxygen, passes into the hydrated peroxide, 

 there are given off, for every volume of oxygen neces- 

 sary to the change from protoxide to peroxide, four 

 volumes of carbonic acid gas. 



But from one volume of oxygen only one volume of 

 carbonic acid can be produced ; and the absorption of 

 one volume of oxygen can only cause, directly, the 

 separation of an equal volume of carbonic acid. Con- 

 sequently, the substance or compound which has lost 

 its oxygen, during the passage of arterial into venous 

 blood, must have been capable of absorbing or com- 

 bining with carbonic acid ; and we find, in point of 

 fact, that the living blood is never, in any state, satu- 

 rated with carbonic acid ; that it is capable of taking 

 up an additional quantity, without any apparent disturb- 

 ance of the function of the globules. Thus, for ex- 

 ample, after drinking effervescing wines, beer, or min- 

 eral waters, more carbonic acid must necessarily be 



